Reforming with oxygen-enriched matter

ABSTRACT

Various embodiments that pertain to oxygen enrichment are described. Oxygen enrichment is shown to allow for independent control of both reformer residence time and the oxygen-to-carbon ratio during reforming. This allows for much better control over the reformer and for significant gains in reformer through-put without negative impacts to reformer performance. Additionally, the use of oxygen enriched reforming is shown to result in enhanced reformer performance, reduced degradation from catalyst poisons (carbon formation and sulfur) and enhanced fuel cell stack performance due to greatly increased hydrogen concentration in the reformate.

CROSS-REFERENCE

This application is a divisional of, and claims priority to, the UnitedStates patent application that was filed on Jun. 1, 2015 with anapplication Ser. No. 14/726,809 and that application is herebyincorporated by reference.

GOVERNMENT INTEREST

The innovation described herein may be manufactured, used, imported,sold, and licensed by or for the Government of the United States ofAmerica without the payment of any royalty thereon or therefor.

BACKGROUND

In oxidative catalytic reforming, a fuel and another substance can beheated and reacted. Examples of this other substance can be steam, air,or water and air. Depending on which substance is used, differentchemical reaction can occur and these chemical reactions can be used toproduce power through an electrochemical energy conversion device oranother energy conversion device. This power can be used to powermachinery as well as be put to other uses.

SUMMARY

In one embodiment, a system comprises a separator and a reformer. Theseparator can be configured to separates an air into an oxygen-enrichedportion and a nitrogen-enriched portion and the reformer can beconfigured to produce an energy from at least a fuel and an oxygen-basedgas. The separator can supply the oxygen-enriched portion to thereformer and the reformer uses the oxygen-enriched portion as theoxygen-based gas.

In one embodiment, a method can be configured to be performed, at leastin part, by at least part of a fuel system. The method comprisesidentifying a desired residence time for a reaction set of a reformerthat is part of the fuel system and causing the reformer to be suppliedwith a matter state at an oxygen-enrichment level to meet the desiredresidence time. The oxygen-enrichment level of the matter state can behigher than an oxygen-enrichment level of air.

In one embodiment, a system comprises a recognition component thatrecognizes an operational temperature of a reformer and a temperaturecomponent that determines that the operational temperature of thereformer is not a desired temperature of the reformer. The system alsocomprises an evaluation component that evaluates the operationaltemperature against the desired temperature to produce an evaluationresult and a modification component that determines how to modify asupply metric for the reformer to achieve the desired temperature of thereformer based, at least in part, on the evaluation result. The systemadditionally comprises a causation component that causes implementationof the supply metric in modified form and a processor that executes atleast one instruction associated with the recognition component, thetemperature component, the evaluation component, the modificationcomponent, the causation component, or a combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Incorporated herein are drawings that constitute a part of thespecification and illustrate embodiments of the detailed description.The detailed description will now be described further with reference tothe accompanying drawings as follows:

FIG. 1 illustrates one embodiment of a fuel cell;

FIG. 2 illustrates one embodiment of a separator;

FIG. 3 illustrates one embodiment of the separator and a reformer;

FIG. 4 illustrates one embodiment of a system comprising a regulator,the separator, and the reformer;

FIG. 5 illustrates one embodiment of a fuel environment;

FIG. 6 illustrates one embodiment of a system comprising a recognitioncomponent, a temperature component, an evaluation component, amodification component, a causation component, and a processor;

FIG. 7 illustrates one embodiment of a system comprising the processorand a non-transitory computer-readable medium;

FIG. 8 illustrates one embodiment of a method comprising eight blocks;

FIG. 9 illustrates one embodiment of a method comprising four blocks;

FIG. 10 illustrates one embodiment of a method comprising four blocks;and

FIGS. 11-22B illustrate embodiments of various charts.

DETAILED DESCRIPTION

A goal of oxidative fuel reforming can be to produce a product stream(e.g., reformate stream) that is rich in hydrogen and carbon monoxide.The overall simplified reactions associated with oxidative catalyticreforming comprise an oxidation reaction (exothermic reaction) Eq. 1, anendothermic steam reforming reaction (endothermic reaction) Eq. 2, and awater-gas-shift reaction (mildly exothermic reaction) Eq. 3.

$\begin{matrix}\left. {{C_{n}H_{m}} + {\frac{n}{2} \cdot O_{2}}}\leftrightarrow{{n \cdot {CO}} + {\frac{m}{2}H_{2}}} \right. & \lbrack 1\rbrack \\\left. {{C_{n}H_{m}} + {{n \cdot H_{2}}O_{(g)}}}\leftrightarrow{{n \cdot {CO}} + {\left( {\frac{m}{2} + n} \right)H_{2}}} \right. & \lbrack 2\rbrack \\\left. {{CO} + {H_{2}O_{(g)}}}\leftrightarrow{{CO}_{2} + H_{2}} \right. & \lbrack 3\rbrack\end{matrix}$

For many terrestrial applications, oxygen for a catalytic oxidativereaction comes from air. Air can comprise of approximately 78.08%nitrogen, approximately 20.95% oxygen, approximately 0.93% argon,approximately 0.035% carbon dioxide and approximately 0.005% other. Over79% of air comprises gases that when reformed do not participate inreforming reactions. These additional gases place a burden on processingequipment (e.g., by way of parasitic power requirements), result inoversized hardware components which negatively impact system size,weight, cost and thermal losses. Increasing the oxygen content of aircan improve the performance of fuel reformers by increasing reactantresidence times, increasing reactant concentration, and eliminatingenergy consumed in heating non-reacting species (e.g. nitrogen). Thereare two primary approaches to oxygen-enrichment of air (although othersmay be used): polymeric membranes and ceramic membranes. Membranes canseparate a feed gas (in this case, air) into an oxygen-enriched streamand a nitrogen-enriched stream through a number of mechanisms, such as:a pressure difference, a concentration difference, a chemical potentialdifference, or an electrical potential difference. Polymermembrane-based air intake systems operate at ambient temperatures andhave been used successfully as oxygen enrichment systems for internalcombustion engine applications and for nitrogen enrichment purposesproviding an inert gas blanket in aircraft fuel compartments.Developments with both ceramic and polymeric membranes can make theapplication of oxygen enrichment of air for combustion and reformingpurposes feasible and of practical interest.

In one embodiment, a catalytic reformer can be used to convert a gaswith oxygen and a fuel into energy that is hydrogen rich or ahydrogen-based chemical compound. The catalytic reformer can have apreferred operating temperature and use part of the fuel to reach thatpreferred operating temperature. The remaining fuel can be used inenergy production. When using an oxygen-enriched gas in comparison toair, less of the fuel can be used to bring the catalytic reformer to thepreferred operating temperature and therefore more fuel can be used forenergy production. Therefore, it can be preferable to useoxygen-enriched gas over air.

Further, when air is used with the catalytic reformer, a relativelylarge amount of nitrogen can be present in the reformer. Nitrogen canact as a diluent and can represent a large volume flow throughout thefuel processing system and fuel cell stack. With this nitrogen in thecatalytic reformer, some of the fuel may not fully chemically react as aresult of short residence times, low operating temperatures, and/or lowreactant concentrations and, therefore, carbon compounds or sulfurpresent in fuels may cause irreparable damage to the catalytic reformer.Alternatively, the oxygen-enriched gas can be produced by nitrogenremoval and the oxygen-enriched gas can be supplied to the catalyticreformer. With less nitrogen, more of the fuel can fully chemicallyreact and, therefore, carbon and sulfur can form compounds that can bebetter tolerated by catalysts in the reformer (e.g. CO, CO₂, H₂S).

The following includes definitions of selected terms employed herein.The definitions include various examples. The examples are not intendedto be limiting.

“One embodiment”, “an embodiment”, “one example”, “an example”, and soon, indicate that the embodiment(s) or example(s) can include aparticular feature, structure, characteristic, property, or element, butthat not every embodiment or example necessarily includes thatparticular feature, structure, characteristic, property or element.Furthermore, repeated use of the phrase “in one embodiment” may or maynot refer to the same embodiment.

“Computer-readable medium”, as used herein, refers to a medium thatstores signals, instructions and/or data. Examples of acomputer-readable medium include, but are not limited to, non-volatilemedia and volatile media. Non-volatile media may include, for example,optical disks, magnetic disks, and so on. Volatile media may include,for example, semiconductor memories, dynamic memory, and so on. Commonforms of a computer-readable medium may include, but are not limited to,a floppy disk, a flexible disk, a hard disk, a magnetic tape, othermagnetic medium, other optical medium, a Random Access Memory (RAM), aRead-Only Memory (ROM), a memory chip or card, a memory stick, and othermedia from which a computer, a processor or other electronic device canread. In one embodiment, the computer-readable medium is anon-transitory computer-readable medium.

“Component”, as used herein, includes but is not limited to hardware,firmware, software stored on a computer-readable medium or in executionon a machine, and/or combinations of each to perform a function(s) or anaction(s), and/or to cause a function or action from another component,method, and/or system. Component may include a software controlledmicroprocessor, a discrete component, an analog circuit, a digitalcircuit, a programmed logic device, a memory device containinginstructions, and so on. Where multiple components are described, it maybe possible to incorporate the multiple components into one physicalcomponent or conversely, where a single component is described, it maybe possible to distribute that single component between multiplecomponents.

“Software”, as used herein, includes but is not limited to, one or moreexecutable instructions stored on a computer-readable medium that causea computer, processor, or other electronic device to perform functions,actions and/or behave in a desired manner. The instructions may beembodied in various forms including routines, algorithms, modules,methods, threads, and/or programs including separate applications orcode from dynamically linked libraries.

FIG. 1 illustrates one embodiment of a fuel cell 100. The fuel cell 100can be a solid oxide fuel cell. Fuel can be supplied to the fuel cell100 in chemical form, such as hydrogen, carbon monoxide, or methane. Thefuel cell 100 will be discussed below.

FIG. 2 illustrates one embodiment of a separator 200. The separator 200can be used to separate air (e.g., gas with about 20.95% oxygen, about78.09% nitrogen, and the remainder being about 0.96% other elements).The separator 200 can separate the air, in one embodiment, through useof a polymer membrane into an oxygen-enriched air and anitrogen-enriched air. The enriched air can be gas that has a higherratio of one type of gas than another gas types. To provide an academicexample, the separator 200 can remove all of the nitrogen. This leavesthe 95.62% of the oxygen and 4.38% of the other elements. The separator200 may not change the quantity of the oxygen (e.g., moles or mass ofoxygen), just the concentration of the produced gas that is theoxygen-enriched air.

FIG. 3 illustrates one embodiment of the separator 200 and a reformer310. The separator 200 can be configured to separate an air 320 into anoxygen-enriched portion 330 (illustrated as oxygen portion 330) and anitrogen-enriched portion 340 (illustrated as nitrogen portion 340). Theoxygen-enriched portion 330 can be supplied to the reformer 310 whilethe nitrogen-enriched air can be discarded or used for another purpose.The reformer 310 can be configured to produce an energy 350 from atleast a fuel 360 (e.g., singular fuel or blended fuel) and anoxygen-based gas such as the oxygen-enriched portion 330. Examplereformer types for the reformer 310 can be a metal reformer or a ceramicreformer (e.g., the reformer 310 can comprise a shell layer, a ceramicmat layer, and a ceramic substrate layer). The energy 350 of thereformer can be supplied to the fuel cell 100 of FIG. 1. In one example,the energy 350 outputted from the reformer 310 can be hydrogen+carbonmonoxide and this is shown as being entered into the fuel cell 100 ofFIG. 1.

Example fuels that can be placed into the reformer 310 can includediesel, JP-5, JP-8, Jet A, kerosene, TS-1, or JP-4. The fuel 360 caninclude carbon as complex hydrocarbons, such as n-paraffin,iso-paraffin, cyclo-paraffin, mono-aromatics, and poly-aromatics.Depending on the fuel type different percentages of at least some of theabove listed complex hydrocarbons can be present. Additionally, sulfurcan be associated with these complex hydrocarbons at a percentagedependent on the fuel used. Examples of sulfur can include thiohene,dibenzo-thiohene, dimethylbenzo-thiophene, and trimethyl-benzothiophene.

A first portion of the fuel 360 can be burned (e.g., oxidized) to bringthe reformer 310 to a specific temperature. At this specific temperaturea second portion of the fuel 360 can be subjected to a chemical reactionto produce the energy 350. A third portion of the fuel 360 can fail tobe burned and fail to be subjected to the chemical reaction. This thirdportion can be a reaction byproduct and can include carbon and/or sulfurthat can build-up on a catalyst and/or react with catalyst materials ofthe reformer 310. Build-up of this carbon and/or sulfur can cause atleast partial deactivation of the reformer 310 and this build-up can beirreversible. Therefore, it can be beneficial to have less unboundcarbon and/or sulfur produced in conversion of the fuel 360 into theenergy 350 by the reformer 310.

The separator 200 can reduce an amount of nitrogen supplied to thereformer 310 and this can lead to less carbon formation. Nitrogen maynot participate in reforming reactions and may act as a diluent forreforming reactants. Nitrogen reduces reactant concentrations, reducesreactant residence time, and absorbs energy. These can have negativeeffects on the performance of the reformer 310. In addition, nitrogencan place a burden on system level processing equipment (e.g., parasiticpower requirements), resulting in oversized components which negativelyimpact system size, weight, cost and thermal losses. Without having toprocess the nitrogen and/or having less nitrogen to process, thereformer 310 can become more efficient at producing the energy 350.Using the oxygen-enriched portion results in less nitrogen, less volumeflow downstream (e.g., reduced component size and/or weight and lessparasitic pumping power used), and more fuel available to create desiredproducts (e.g., reformate) such as H₂ and CO as well as an increase inconcentration of these products.

The reformer 310 can have a preferred operating temperature (actualtemperature or a preferred temperature range) that can be a most optimaltemperature for conversion of the fuel 360 into the energy 350. The lessof the fuel 360 that is used to bring the reformer 310 to the preferredtemperature the more fuel 360 that can be used to produce the energy350. The reformer 310 can use the air 320 or the oxygen-enriched portion330. In one embodiment, the reformer 310 is configured to use theoxygen-enriched portion 330 and a first quantity of the fuel 360 tocreate a set temperature and/or can be configured to use the air 320 anda second quantity of the fuel 360 to create the set temperature. Thefirst quantity of the fuel 360 is smaller than the second quantity offuel 360—therefore less of the fuel is used to create the settemperature (e.g., the preferred operating temperature) when usingoxygen enriched air. With this embodiment, the fuel 360 can be used toproduce the energy 350 by being brought to the set temperature. The settemperature can be a temperature (e.g., an optimal temperature) at whichthe fuel 360 chemically reacts in order to produce the energy 350. Sinceless of the fuel 360 is used with the oxygen-enriched portion 330 thanthe air 320 to reach the set temperature more of the fuel can bededicated to energy production. To put another way, with oxygen-enrichedportion 330, more of the fuel 360 is used to produce energy as opposedbeing used to reach the set temperature in comparison to reforming withair; reforming with the oxygen-enriched portion 330 can make the system300 more efficient. Therefore, the reformer 310 can be configured to usemore of the fuel 360 to produce the energy 350 with the oxygen-enrichedportion 330 over the air 320 since less of the fuel 360 is used tocreate the set temperature. An amount of the energy 350 produced by thereformer 310 can be greater with the oxygen-enriched portion 330 thanthe air 320 since more of the fuel 360 is available because less of thefuel 360 is used to create the set temperature

A simplified view of oxidative reforming can be depicted as a two-actionprocess, with the first action comprising oxidizing (e.g., burning)reactions and the second action can comprise fuel reforming reactions.The first action of oxidation provides heat to bring the reformer to adesired temperature and to support reforming reactions of the secondaction. As described here, reforming reactions can be predominantlyendothermic (e.g., require heat). Considering the above, a fixedquantity of the fuel 360 can be used by the reformer 310 under twodifferent scenarios: (1) reforming using oxygen-enriched air, and (2)reforming with air. The first quantity of the fuel 360 (e.g., supportingoxidative reactions with the oxygen-enriched portion 330) and a thirdquantity of the fuel 360 (e.g., supporting reforming reactions with theoxygen-enriched portion 330) added together equals the single fuelquantity and, similarly, a second quantity of the fuel 360 (e.g.,supporting oxidative reactions with the air 320) and a fourth quantityof the fuel 360 (e.g., supporting reforming reactions with the air 320)added together equals the single fuel quantity. Due to the firstquantity of the fuel 360 (e.g., supporting oxidative reactions with theoxygen-enriched portion 330) being smaller than the second quantity offuel 360 (e.g., supporting oxidative reactions with the air 320), thethird quantity of the fuel 350 (e.g., supporting reforming reactionswith the oxygen-enriched portion 330) is greater than the fourthquantity of fuel 350 (e.g., supporting reforming reactions with the air320). The reformer 310 can be configured to use the third quantity ofthe fuel 360 (e.g., supporting reforming reactions with theoxygen-enriched portion 330) to produce the energy 350 and can beconfigured to use the fourth quantity of the fuel 360 (e.g., supportingreforming reactions with the air 320) to produce the energy 350. In viewof this, the reformer 310 can take a total quantity of the fuel 360 anduse one part of the fuel to reach the set temperature and another partof the fuel 360 to produce the energy 350. If less of the fuel 360 isused to reach the set temperature, then more of the fuel can be used forproduction of the energy 350. Therefore, for a fixed quantity of fuel360, more energy 350 can be produced with oxygen-enriched air than canbe produced with air alone.

Capacity (e.g., through-put or process thermal rating) of the reformer310 can also be significantly improved by using the oxygen-enrichedportion 330. A capacity of the reformer 310 using the oxygen-enrichedportion 330 can be greater than a capacity of the reformer 310 using theair 320 since the nitrogen is reduced (e.g., at least partiallyremoved). The energy 350 produced by the reformer 310 from the fuel 360and the oxygen-enriched portion 330 can be greater than an energyproduced by the reformer 310 from the fuel 360 and the air 320. Asdiscussed above, the air 320 can be about 20.95% oxygen and about 78.09%nitrogen. For example purposes, this can be addressed as air being 20%oxygen and 80% nitrogen. If all the nitrogen is removed, then the oxygenconcentration can be approximately five times greater for theoxygen-enriched portion 330 than air 320 with the same quantity (e.g.,moles or mass) of oxygen being provided.

In one embodiment, a first reaction time (e.g., residence time or spacetime) in the reformer 310 with the oxygen-enriched portion 330 is longerthan a second reaction time in the reformer with the air 320. Reactiontime can be an average time a substance would reside within the reformer310. This time can be mathematically defined as the reformer volumedivided by the volume flow into the reformer 310. The reaction times aswell as reactant concentrations can have an important influence onreaction kinetics that directly affect the production of the energy 350.The first and second reaction times are average lengths of time that thefuel 360, air 320 (or enriched-oxygen air 330) have to react within thereformer 310. A lesser amount of a catalyst-detrimental element (e.g.,carbon or sulfur compounds) is produced from a reaction over the firstreaction time (e.g., with oxygen-enriched air 330) than from thereaction over the second reaction time (e.g., with air 320). A carbon orsulfur detrimental element can be a carbon or sulfur containingmolecular species or element that can react with a reforming catalyst orattach to a reforming catalyst, degrading or destroying catalyticactivity (e.g., poisoning the catalysts). Longer reaction times directlyhelp to fully convert the fuel 360 which minimizes the production ofcompounds that lead to carbon formation and deactivation of catalysts. Aprominent contribution of oxygen-enrichment to sulfur removal is thatoxygen enrichment results in higher hydrogen concentrations in thereformer 310 which removes elemental sulfur by: H₂+S→H₂S; thuspreventing sulfur from forming metal sulfides with catalysts anddeactivating catalysts. Increased residence time can also positivelyinfluence the above reaction. With the oxygen-enriched portion 330 thereis a longer reaction time and in turn more fuel is produced to theenergy 350 while less of the fuel 360 remains un-reacted. With less ofthe fuel 360 being un-reacted, less of the catalyst-detrimental elementis produced. Less production of the catalyst-detrimental element canmean less irreversible damage to the reformer 310.

As discussed above, the separator 200 can separate the oxygen-enrichedportion 330 and the nitrogen-enriched portion 340 from the air 320. Withthe oxygen-enriched portion 330 and the fuel 360, the reformer canproduce hydrogen through chemical reactions. In fuel reforming, whereoxygen is obtained from air, nitrogen in air acts simply as a diluentfor the products of reformation (e.g., energy 350). Withoxygen-enrichment, less nitrogen is provided to the reformer 310,resulting in higher reactant (e.g., fuel, water, oxygen-enriched air)concentrations within the reformer 310 that produces higher hydrogenconcentrations in the energy 350.

FIG. 4 illustrates one embodiment of a system comprising a regulator410, the separator 200, and the reformer 310. The regulator 410 can beconfigured to regulate a flow rate (e.g., volume over time) and pressure(e.g., pounds per square inch) of the oxygen-enriched portion to thereformer 310. While depicted as regulating flow rate and pressure of theair 320 to the separator 200, the regulator 410 can physically functionbetween the separator 200 and the reformer 310 to regulate the flow rateand concentration of oxygen in the oxygen-enriched portion 330. However,the separator 200 may function such that it operates based ondifferential pressure produced from the regulator 410. The regulator 410can comprise a valve to physically and actively manage how the flow andpressure occurs in accordance with the flow rate and desired oxygenconcentration as well as various components, such as an identificationcomponent and a determination component, and a controller. Theidentification component, the determination component, the controller,or a combination thereof can be implemented separate from the regulator410. The identification component can be configured to identify apreferred temperature for the reformer 310 with regard to fuelefficiency. The determination component can be configured to determinespecific flow rate and oxygen concentration values to cause the reformer310 to function at the preferred temperature. The controller can causethe regulator 410 to use the specific flow rate value as the flow rate.The regulator 410 can also regulate flow of the fuel 360 based upondemand.

The fuel 360 can be a specific fuel type that functions most effectivelyat a set temperature. The identification component can identify thistemperature by, for example, sending a request to a fuel supply unit forfuel information and reading a response. The determination component candetermine the specific flow rate through calculation. In one example,the identification can be that the fuel 360 functions most efficientlyat X degrees. The determination component can determine how much of theoxygen-enriched portion 330 per second (a rate), based on oxygenconcentration (otherwise known as oxygen enrichment) the reformer 310would use to reach the temperature (e.g., without having to use the fuel360 to reach temperature). The controller can cause the regulator 410 touse this rate.

The system 400 can function with feedback capabilities. In one example,if the reformer 310 is functioning at too hot of a temperature, then theregulator 410 can lower the air flow rate. If the reformer 310 is thenusing too much of the fuel 360 to reach the temperature, then theregulator 410 can increase the air pressure which will increase theoxygen concentration from the separator (e.g., increased oxygenenrichment).

FIG. 5 illustrates one embodiment of a fuel system 500. The fuel system500 can be considered an oxygen-enriched fuel reforming system. The fuelsystem 500 can function in accordance with various aspects disclosedherein to produce the energy 350 of FIG. 3. In one example, the membraneseparator shown in the fuel system 500 can be the separator 200 of FIG.2 and the autothermal reformer is the reformer 310 of FIG. 3. This fuelsystem 500 can be used to practice oxygen-enriched autothermal fuelreforming. Use of the fuel system 500 can produce, by way of themembrane separator, the oxygen-enriched portion 330 of FIG. 3 from air320 of FIG. 3. Use of the membrane separator can lead to reducedparasitic pumping losses which increase reforming efficiency, reducedelement size for an element of the fuel system 500 and/or can produce adrop in pressure of the fuel system 500. In addition, use of themembrane seperator can lead to increased reformer operating temperature(e.g., optimize reformer temperature with fuel provided), increasereactant resident time (e.g., match reactant resident time with fuelprovided), and an increased hydrogen partial pressure within thereformer 310 of FIG. 3.

With the fuel system 500 two regulators are illustrated—a regulatorbefore the membrane separator and a pressure regulating valve. Eitherone of these can be considered the regulator 410 of FIG. 4. In addition,the combination of the two can also be considered the regulator 410 ofFIG. 4. Further, the regulator 410 of FIG. 4 discusses controlcapabilities and these control capabilities can be performed, in oneembodiment, by the controller illustrated as part of the fuel system500. Therefore, the regulator illustrated as part of FIG. 5 can be amechanical regulator.

FIG. 6 illustrates one embodiment of a system 600 comprising arecognition component 610, a temperature component 620, an evaluationcomponent 630, a modification component 640, a causation component 650,and a processor 660. The recognition component 610 can recognize anoperational temperature of a reformer (e.g., the reformer 310 of FIG.3). The temperature component 620 can determine that the operationaltemperature of the fuel cell is not a desired temperature of thereformer. The desired temperature of the reformer can be a specifictemperature or a temperature range while the operational temperature canbe too hot or too cold. The evaluation component 630 can evaluate theoperational temperature against the desired temperature to produce anevaluation result. The modification component 640 can determine how tomodify a supply metric for the reformer to achieve the desiredtemperature of the reformer based, at least in part, on the evaluationresult. In one example, the evaluation result can be that theoperational temperature is not hot enough. In view of this, themodification component 640 can determine that an optimal way to raisethe operational temperature is by increasing oxygen concentration of anoxygen-enriched gas to the reformer. The causation component 650 cancause implementation of the supply metric in modified form, such ascausing the enrichment concentration to be increased. The processor 660can execute at least one instruction associated with the recognitioncomponent, the temperature component, the evaluation component, themodification component, the causation component, or a combinationthereof.

In an illustrative example, the system 600 can monitor operation of thereformer and as part of this monitoring can determine that theoperational temperature is too high. Based on this high temperature, themodification component 640 can select an oxygen enrichment level ofoxygen-enriched gas as the supply metric to change. Depending on logicused by the system 600, the oxygen enrichment level can be eitherincreased or decreased.

The operational temperature can be higher or lower than the desiredtemperature such that the operational temperature indicates that anundesirable product is produced at a level that is unacceptable.Initially, a higher operating temperature can indicate that theundesirable product is produced. An example of this can be the initialselective deactivation of catalysts towards endothermic reactions,resulting in a temperature rise. This can be considered a short termresult. After a period of time, the undesirable product begins tocompletely deactivate the catalyst of the reformer 310 of FIG. 3. Withthis complete deactivation, both endothermic and exothermic reactionsare degraded and the operational temperature can become lower over thelonger term. The system 600 can function such that a change in theoperational temperature, either higher or lower, can be interpreted as aformation of the undesirable product and corrective action can then betaken.

The undesirable product can be graphic carbon. Olefins can be aprecursor for formation of graphic carbon. An increase or decrease intemperature of the reformer 310 of FIG. 1, such as an increase ordecrease without changing a supply metric, can be an indicator thatolefins are being produced and in turn that graphic carbon is beingproduced. Prolonged exposure to graphic carbon can cause irrevocabledamage to the reformer 310 of FIG. 3. With this, a rise or drop inoperational temperature against the desired temperature can beindicative that olefins are being produced and the system 600 canfunction to lower olefin concentration and ultimately to eliminate thegraphic carbon within the reformer 310 of FIG. 3. In one example, whenthe temperature component 620 determines that the temperature is toohigh or too low, the evaluation component 630 and the modificationcomponent 640 can process information to determine how to correct thissituation. As an example, the evaluation component 630 and themodification component 640 can conclude that if the oxygen enrichmentlevel were greater, then less olefins would be produced and in turn theoperational temperature would be lowered or raised. Therefore, thesupply metric can be modified such that the oxygen enrichment level forthe oxygen-enriched gas is increased and thus the undesirable product isproduced at a level that is acceptable.

The oxygen-enriched gas, as opposed to air, can result in an increase inhydrogen concentration, as well as an increase in concentration of otherelements (e.g., non-nitrogen elements), in the reformer 310 of FIG. 3and downstream of the reformer 310 of FIG. 3. Increased hydrogenconcentration within the reformer 310 promotes hydrogen reduction ofundesirable products (e.g. carbon and sulfur). At least part of thehydrogen chemically interacts with the undesirable product to lower apermanent negative impact on the reformer 310 of FIG. 3 from theundesirable products. With this chemical interaction, at least part ofthe undesirable product can be mitigated and not impact the reformer 310of FIG. 3.

FIG. 7 illustrates one embodiment of a system 700 comprising theprocessor 660 (e.g., a general purpose processor or a processorspecifically designed for function in the fuel system 500 of FIG. 5,such as at least part of the controller) and a non-transitorycomputer-readable medium 710. In one embodiment, the computer-readablemedium 710 is communicatively coupled to the processor 660 and stores acommand set executable by the processor 660 to facilitate operation ofat least one component disclosed herein (e.g., the recognition component610 of FIG. 6). In one embodiment, at least one component disclosedherein (e.g., the temperature component 620 of FIG. 6) can beimplemented, at least in part, by way of non-software, such asimplemented as hardware by way of the system 700. In one embodiment, thecomputer-readable medium 710 is configured to store processor-executableinstructions that when executed by the processor 660 cause the processor660 to perform a method disclosed herein (e.g., the methods 800-1000addressed below). In one example, the computer-readable medium 710 andthe processor 660 form at least part of a fuel processing controller(e.g., the controller illustrated in the system 500 of FIG. 5 thatmanages at least part of the remaining system 500 of FIG. 5). The fuelprocessing controller can perform a method disclosed herein.

FIG. 8 illustrates one embodiment of a method 800 comprising eightblocks 810-880. The method 800 can be configured to be performed, atleast in part, by at least part of the fuel system 500 of FIG. 5. In oneexample, the fuel processing controller can perform at least part of themethod 800.

At 810 a fuel can be selected and/or identified (e.g. identifying a fueltype for the fuel system 500 of FIG. 5). In one example, a reformer(e.g., the reformer 310 of FIG. 3) can be configured to work withmultiple fuel types. Depending on the fuel type, the reformer can havean optimum (or other beneficial or improved) reformer temperature aswell as a minimum residence time. Also at 810, a load demand can besensed for the fuel system 500 of FIG. 1. This load demand can set afuel flow rate, oxygen-to-carbon ratio, minimum residence time (e.g.,determined from fuel type), and optimum oxygen enrichment. Part ofsensing the load demand can be identifying a desired residence time fora reaction set of the reformer that is part of the fuel system 500 ofFIG. 5 and/or setting the desired residence time based, at least inpart, on the fuel type.

At 820, the reformer temperature can be set (e.g., setting anoperational temperature of the reformer by way of a molaroxygen-to-carbon ratio, where the temperature of the reformer influencesthe desired residence time for the reaction set). This can be donethrough adjusting a molar oxygen-to-carbon ratio by way of flow rate toachieve this reformer temperature. Additionally at 820,oxygen-enrichment level can be adjusted to meet the minimum residencetime.

At 830, a check can take place to determine if the oxygen enrichmentmatches the optimum value for the residence time associated with thefuel type. If not, then the method 800 can continue to 840 to adjust theenrichment for optimization. After 840 occurs or if the check 830determines that the enrichment is at an optimum, check 850 can occur todetermine if the temperature is at a set point (e.g., optimum reformertemperature). If the temperature is not at a set point, then the method800 can return to 820 to reset the reformer temperature. A similar check860 can occur to determine if the fuel flow rate is correct. If not,then the fuel flow rate can be adjusted (e.g., as part of 860) and themethod can return to 820 for modification if appropriate.

Once the checks 830 and 850-860 determine modification is notappropriate, then the fuel system 500 of FIG. 5 can run at 870. As partof 870 there can be causing the reformer to be supplied with a matterstate at an oxygen-enrichment level to meet the desired residence timeand/or causing the reformer to be supplied with a fuel at a fuel rate,where the reformer uses the fuel and the matter state to perform thereaction set. The oxygen-enrichment level of the matter state can behigher than an oxygen-enrichment level of air. The matter state can beproduced from supplying the air through a separator that produces thematter state at the oxygen-enrichment level that is higher than air andthat produces a matter state with a nitrogen-enrichment level that ishigher than air

The reformer can be monitored at 880 (e.g., monitored periodically, suchas every X seconds where X is an integer). As part of this monitoring atemperature of the reformer can be monitored. As a result, amodification can occur (e.g., the method 800 can return from 880 to 820or 840) such as an oxygen-enrichment level. With this, 880 can comprisechecking if the reaction set is functioning with the desired residencetime (e.g., by way of measuring inlet flow rate of the reformer 310 ofFIG. 3). When the method 800 returns to 820 determining how to changethe oxygen-enrichment level to meet the desired residence time andsupply of a matter state at the oxygen-enrichment level in view of thechange to meet the desired residence time can occur.

FIG. 9 illustrates one embodiment of a method 900 comprising four blocks910-940. At 910 a state of the reformer 310 of FIG. 3 can be observed.In one example, a temperature of the reformer 310 of FIG. 3 can beobserved to determine carbon production or carbon production can bemonitored by way of another manner. A check can take place at 920 todetermine if the state is acceptable, such as being in an acceptablerange. If the check results such that the state is acceptable (e.g., acorrect state), then observation can continue and in essence actions 910and 920 can loop continuously. If the check results such that the stateis not acceptable (e.g., a wrong state), then there can be adetermination on what correction to make at 930. This determination canbe based on the actual state, deviation from an acceptable state,available corrective measures, etc. This correction can be implementedat 940 and the method 900 can return to 910 (e.g., even as 930 and 940observation at 910 continues or observation at 910 pauses when the checkresults in the state being not acceptable and then resumes afterimplementation 940). Returning to the temperature example discussedearlier in this paragraph, if the temperature is too high or too low,then a determination can be made to increase oxygen enrichment level,air flow level, etc. and a correction based on this determination can beimplemented. This determination can have a goal of making the stateacceptable in a shortest amount of time, using a fewest amount ofresources, etc.

FIG. 10 illustrates one embodiment of a method 1000 comprising fourblocks 1010-1040. The method 1000 can be how the separator 200 of FIG. 2operates. At 1010 the separator 200 of FIG. 2 can receive air. This aircan be at an air flow rate and pressure selected by a componentdisclosed herein, such as selected for a certain performance from thereformer 310 of FIG. 3. The separator 200 of FIG. 2 can separate the airinto an oxygen-enriched part and a nitrogen-enriched part at 1020. Thisseparation may not be complete separation in that the oxygen-enrichedpart will have some nitrogen and the nitrogen-enriched part will havesome oxygen, but the concentrations will be improved (e.g., enriched).At 1030 the oxygen part can be transferred to the reformer 310 of FIG. 3for use in energy production while at 1040 the nitrogen-enriched partcan be transferred away from the reformer 310 of FIG. 3, such as put ina fuel tank over air for safety purposes or used in bed purging.

While the methods disclosed herein are shown and described as a seriesof blocks, it is to be appreciated by one of ordinary skill in the artthat the methods are not restricted by the order of the blocks, as someblocks can take place in different orders. Similarly, a block canoperate concurrently with at least one other block.

FIG. 11 illustrates one embodiment of a chart 1100. The chart 1100 showsthe oxygen and nitrogen portions from the air 320 of FIG. 1. As thenitrogen is removed, the ratio of nitrogen-to-oxygen decreases while theoxygen enrichment increases.

FIGS. 12A-B illustrate one embodiment of two charts 1210 and 1220. Thechart 1210 addresses a relationship between molar oxygen to carbon (O/C)ratio and space time under conditions of: 5.9 ml/min. (3.33 kWth),S/C=2.0, O/C of 1.0; 5% reformer thermal losses. Reformer inlettemperature of 425° C. The chart 1220 addresses a relationship betweenmolar oxygen to carbon (O/C) ratio and space time with oxygen-enrichmentunder conditions of: 5.9 ml/min. (3.33 kWth), S/C=2.0, 0/C of 1.0; 5%reformer thermal losses, and reformer inlet temperature of 425° C. Thesecharts illustrate that a significant consequence of oxygen enrichment isthat it decouples a molar oxygen to carbon ratio (O/C) and reformerspace time. This allows the ability to maintain an optimum molar ratioof oxygen and carbon (e.g., from the fuel 360 of FIG. 3) whileindependently optimizing residence time.

FIGS. 13A-D illustrate one embodiment of four charts 1310-1340. Thesefour charts illustrate how performance can be improved with increasingoxygen enrichment. Three lines are shown in the charts 1310-1340—diamondfor 3.33 kW_(th), square for 5.00 kW_(th), and circle for 6.67kW_(th)—and in charts 1330 and 1340 triangles are for 8.33 kW_(th). Thisshows that as oxygen enrichment levels (EN) are increased, fuelconversion becomes more efficient and reactions can lose kinetic or masstransfer limitations, and the capacity (e.g, fuel throughput or processthermal rating) can be greatly increased. Therefore, charts 1310-1340address an influence of oxygen-enrichment on fuel conversion underexperimental conditions of: S/C=2, fuel consisting of 70 vol % dodecane,20 vol % toluene, 10 vol % decalin; fuel flow of 5.9 ml/min. (3.33kW_(th)), 8.85 ml/min (5.0 kW_(th)), and 11.8 ml/min. (6.67 kW_(th)),and 14.76 ml/min. (8.33 kW_(th)); enrichment number (Ψ) of 0.477, 1.0,1.432, and 1.91; with 425° C. entrance temperature.

FIG. 14 illustrates one embodiment of a chart 1400. The chart 1400 showshow hydrogen concentration changes as a function of oxygen enrichmentand in turn an effect of oxygen enrichment on hydrogen concentration inthe reformate stream. This is shown under conditions of: S/C=2, fuelconsisting of 70 vol % dodecane, 20 vol % toluene, 10 vol % decalin;fuel flow of 5.9 ml/min. (3.33 kW_(th)), enrichment number (Ψ) of 0.477,1.0, 1.432, and 1.91; with 425° C. entrance temperature.

FIG. 15 illustrates one embodiment of a chart 1500. The chart 1500 showsthat with increased hydrogen concentration, fuel cell efficiencyincreases and fuel utilization increases while the hydrogen flow rateper kWe output decreases for a fixed fuel cell power output. The chart1500 therefore shows the effect of hydrogen concentration entering thefuel cell stack on the overall stack efficiency based on the lowerheating value of hydrogen. Initial stack voltage assumed at 0.7volts/cell, with an anode hydrogen entrance concentration of 33.9% (drybasis, mole %), cell temperature of 800° C., pressure of 1 atm, andsteam and oxygen concentrations are assumed constant. Fuel utilizationis based on maintaining 15% (mole %)hydrogen in the exit of the fuelcell anode. One equation that can be used in conjunction with the chart1500 is shown below as equation 4. Equation 4 shows analytically theeffect of hydrogen concentration of fuel cell efficiency (η_(LHV)).

$\begin{matrix}{\eta_{LHV} = {u_{fuel} \cdot \left( {{\frac{E_{1} - {{\frac{RT}{2} \cdot \ln}\frac{\left( X_{H_{2}} \right)_{2}}{\left( X_{H_{2}} \right)_{1}}}}{1.25} \cdot 100}\%} \right)}} & \lbrack 4\rbrack\end{matrix}$

where, u_(fuel) Nernst the anode fuel utilization, E₁ is the Nest cellvoltage at condition 1, R is the ideal gas constant (8.314 J/mol-K),

is Faraday's constant (96,485 Coulombs/mol), and Xi is the partialpressure of i, subscripts 1 and 2 refer to two conditions.

FIGS. 16A-B illustrate one embodiment of two charts 1610 and 1620. Thecharts 1610 and 1620 address oxygen enrichment's influence on optimizingsystem efficiency, capacity (e.g., fuel through-put or process thermalrating), size and weight under experimental conditions of: S/C=2, fuelconsisting of 70 vol % dodecane, 20 vol % toluene, 10 vol % decalin;fuel flow of 5.9 ml/min. (3.33 kW_(th)), 8.85 ml/min (5.0 kW_(th)), and11.8 ml/min. (6.67 kW_(th)), and 14.76 ml/min. (8.33 kW_(th));enrichment number (Ψ) of 0.477, 1.0, 1.432, and 1.91; with 425° C.entrance temperature. The chart 1610 shows reformer efficiency againstoxygen enrichment (shown as enrichment number). Where the enrichmentnumber is defined by equation 5 below:

$\begin{matrix}{{{{Enrichment}\mspace{14mu}{{number}(\Psi)}} \equiv \frac{{Percentage}\mspace{14mu}{oxygen}\mspace{14mu}{in}\mspace{14mu}{enriched}\mspace{14mu}{air}}{{Percentage}\mspace{14mu}{oxygen}\mspace{14mu}{in}\mspace{14mu}{air}}} = \frac{X\mspace{14mu}\%}{20.95\%}} & \lbrack 5\rbrack\end{matrix}$

The chart 1620 shows reformer volume (e.g., volume of the reformer 310of FIG. 3) against oxygen enrichment. Use of oxygen enrichment can allowoptimization of a reformer according to maximum efficiency, maximumcapacity, and minimal size and weight. Reformer volume can be defined asthe ratio of reformer volume with oxygen-enrichment to reformer volumewith air.

FIG. 17 illustrates one embodiment of a chart 1700. The chart 1700addresses an effect of oxygen enrichment on reformer operatingtemperature under experimental conditions of: 100 vol % n-dodecane, 3.3kWth (5.9 ml/min.), O/C=1.0, S/C=2.0; with 425° C. entrance temperature.As shown in the chart 1700, increasing oxygen enrichment results inhigher reformer temperature, such as exit and peak reformertemperatures. Reactions are a strong function of temperature, which isshown through equation 6 below:

$\begin{matrix}{k = {{A\left( \frac{T}{T_{0}} \right)}^{\beta}\exp^{- {\lbrack\frac{E_{a}}{RT}\rbrack}}}} & \lbrack 6\rbrack\end{matrix}$where, k is the rate constant, A is the pre-exponential factor, T is thereaction temperature, To is a reference temperature, β is a numberdetermined experimentally, E_(a) is the activation energy, and R is thegas constant. In view of this, higher temperatures can result inincreased reactions over a fixed unit of time.

FIG. 18 illustrates one embodiment of a chart 1800. The chart 1800addresses an effect of oxygen enrichment on residence time underexperimental conditions of: 100 vol % n-dodecane, 3.3 kWth (5.9ml/min.), O/C=1.0, S/C=2.0; with 425° C. entrance temperature. The chart1800 compares space time against oxygen enrichment. Increased oxygenenrichment results in longer space time which allows slow reactions togo to completion (e.g., slow reactions that do not go to completionresult can result in carbon formation within the reformer 310 of FIG.3).

FIG. 19 illustrates one embodiment of a chart 1900. The chart 1900 showsthat with oxygen enrichment, hydrogen concentration is increased as isthe hydrogen production rates. With this, the chart 1900 shows an effectof oxygen enrichment on hydrogen concentration in the reformate streamunder experimental conditions of: 100 vol % n-dodecane, 3.3 kWth (5.9ml/min.), O/C=1.0, S/C=2.0; 425° C. entrance temperature. This hydrogencan function as a reducing agent within the reformer that mitigates theformation of solid carbon and sulfur that otherwise could combine withcatalyst materials resulting in catalyst deactivation.

FIG. 20 illustrates one embodiment of a chart 2000. The chart 2000 showsolefin concentration production and olefin molar production as afunction of oxygen enrichment. Chart 2000 addresses an effect of oxygenenrichment on carbon formation (olefin concentration is a predictor ofcarbon formation) in reformate under experimental conditions of: 100 vol% n-dodecane, 3.3 kWth (5.9 ml/min.), O/C=1.0, S/C=2.0; with 425° C.entrance temperature. Increased oxygen enrichment can lead to reducedolefin production and in turn reduced carbon production due to longerreaction time causing more olefins to be converted. In addition,increased hydrogen can remove carbon that is produced through thefollowing reaction: C+2H₂→CH₄.

FIGS. 21A-B illustrate one embodiment of two charts 2110 and 2120. Thecharts 2110 and 2120 address an effect of oxygen enrichment on carbonformation in reformate. This is based on equilibrium modeling underconditions of: 100 vol % n-dodecane, 3.3 kWth (5.9 ml/min.), O/C=1.0,S/C=2.0; with 425° C. entrance temperature. The chart 2110 showsreduction is solid carbon formation and an increase in hydrogen as afunction of increased oxygen enrichment. The chart 2120 shows increasedreformer operating temperature and in turn faster reactions, increasedreformer space time that allow reactions to go to completion or furtherinto completion, as well as higher concentration of water enhancingsteam reforming reactions such as CH₄+H₂O→3H₂+CO which improves fuelconversion.

FIGS. 22A-B illustrate one embodiment of two charts 2210 and 2220. Thecharts 2210 and 2220 address effects of carbon formation on peakreformer operating temperatures under conditions of: straight paraffinickerosene (SPK) with 1-methylnaphthalene added at indicated weightpercentages (wt %), 2.14 kWth (3.0 ml/min.), molar O/C=1.05, molarS/C=1.3. The charts 2210 and 2220 show that as carbon formation rises(seen as a rise in olefin concentration), reformer peak temperaturerises. Modifying the oxygen enrichment can mitigate temperature changesand reduce carbon formation. In view of this, a change in the reformercan indicate an onset of catalyst deactivation through carbon formationand/or sulfur poisoning. Oxygen enrichment can be used as a tool tomitigate these deactivation mechanisms.

What is claimed is:
 1. A method configured to be performed by acontroller of a fuel system, the method comprising: identifying adesired residence time for a reaction set of a reformer that is part ofthe fuel system; and causing the reformer to be supplied with a matterstate at an oxygen-enrichment level to meet the desired residence time,setting an operational temperature of the reformer by way of a molaroxygen-to-carbon ratio; identifying a fuel type for the fuel system; andsetting the desired residence time based, at least in part, on the fueltype and inlet flow rate, wherein the oxygen-enrichment level of thematter state is higher than an oxygen-enrichment level of air, whereinthe reaction set includes catalytic reforming, wherein causing thereformer to be supplied with a matter state at an oxygen-enrichmentlevel is achieved through directing the matter state to be suppliedthrough a membrane separator, wherein the temperature of the reformerinfluences the desired residence time for the reaction set.
 2. Themethod of claim 1, comprising: checking if the reaction set isfunctioning with the desired residence time by way of measuring inletflow rate of the reformer; determining how to change theoxygen-enrichment level to meet the desired residence time when thecheck results that the reaction set is not functioning with the desiredresidence time; and causing supply of the matter state at theoxygen-enrichment level in view of the change to meet the desiredresidence time.
 3. The method of claim 2, where the matter state isproduced from supplying the air through a separator that produces thematter state at the oxygen-enrichment level that is higher than air andthat produces a matter state with a nitrogen-enrichment level that ishigher than air.
 4. The method of claim 2, comprising checking if thereformer is operating at a set temperature point; determining how tochange operation of the reformer when the temperature check results thatthe reformer is not operating at the set temperature point; and changingthe operation of the reformer in accordance with the determination. 5.The method of claim 4, where changing the operation of the reformer inaccordance with the determination comprises changing a molaroxygen-to-carbon ratio of the reformer.
 6. The method of claim 5, wherethe molar oxygen-to-carbon ratio is changed by changing a flow rate ofthe supplied matter state.
 7. The method of claim 1, comprising: causingthe reformer to be supplied with a fuel at a fuel rate, where thereformer uses the fuel and the matter state to perform the reaction set.8. The method of claim 7, where the matter state is produced fromsupplying the air through a separator that produces the matter state atthe oxygen-enrichment level that is higher than air and that produces amatter state with a nitrogen-enrichment level that is higher than air.9. The method of claim 7, comprising: determining a sensed load demandof the reformer; and determining a fuel flow rate based, at least inpart, on the sensed load demand, where the reformer is supplied with thematter state at the determined fuel flow rate.
 10. The method of claim1, wherein the produces a matter state with a nitrogen-enrichment levelthat is higher than air.
 11. The method of claim 1, comprising:monitoring a functional temperature of the reformer; comparing thefunctional temperature of the reformer against the operationaltemperature of the reformer to produce a comparison result; determiningif the comparison result is sufficient to warrant a change in the supplyof the matter state to the reformer; deciding a manner of change whenthe determination is that the comparison result is sufficient; andcausing implementation of the change.
 12. The method of claim 11, wherethe change is modification of a flow rate at which the matter state issupplied to the reformer.
 13. The method of claim 11, where the changeis modification of a pressure at which the matter state is supplied tothe reformer.